bagman

A small bit of code to allow Ouster OS1 data to be exported from ROS to an external C++ program using rosbridge. It should be modifiable to fit any ROS topic you want to make available to some external (potentially remote) process, though I don't claim that this is the most efficient way of doing so.*

These instructions are for Ubuntu 18.04, or 20.04 as noted. Melodic is the release name for 18.04, and Noetic is the release for 20.04. Anywhere melodic is used in a command substitute noetic or whatever the appropriate name is which corresponds to your distribution.

This repo includes modified code from easywsclient, which was published under the MIT license. A copy of the copyright notice and license is available in the easyws directory.

Install ROS

These instructions are directly from the ROS wiki

sudo sh -c 'echo "deb http://packages.ros.org/ros/ubuntu $(lsb_release -sc) main" > /etc/apt/sources.list.d/ros-latest.list'

sudo apt-key adv --keyserver 'hkp://keyserver.ubuntu.com:80' --recv-key C1CF6E31E6BADE8868B172B4F42ED6FBAB17C654

sudo apt update

sudo apt install ros-melodic-desktop-full

You shouldn't need the full install but I didn't test it with the bare bones package

Also install rosbridge

sudo apt install ros-melodic-rosbridge-suite

echo "source /opt/ros/melodic/setup.bash" >> ~/.bashrc
source ~/.bashrc

For Ubuntu 18.04:

sudo apt install python-rosdep python-rosinstall python-rosinstall-generator python-wstool build-essential

For Ubuntu 20.04:

sudo apt install python3-rosdep python3-rosinstall python3-rosinstall-generator python3-wstool build-essential

sudo rosdep init
rosdep update

Building the Ouster PacketMsg

You need to build the Ouster PacketMsg and make it available to ROS.* One way to accomplish this is building Ouster's sample node.

source /opt/ros/melodic/setup.bash
git clone https://github.com/ouster-lidar/ouster_example.git
export CMAKE_PREFIX_PATH=path/to/ouster_example

Note that path/to/ouster_example is where you cloned the repo

mkdir -p myworkspace/src && cd myworkspace && ln -s /absolute/path/to/ouster_example ./src/ && catkin_make -DCMAKE_BUILD_TYPE=Release

echo "source path/to/myworkspace/devel/setup.bash" >> ~/.bashrc
source devel/setup.bash

Building this repo

This project uses Make

make

Running the server and demo program

There are several steps to launching the rosbridge server and demo program, which require multiple terminals.

In the first terminal launch roscore

roscore

In a second terminal, begin the playback of the rosbag

rosbag play path/to/some/rosbag.bag --pause -r 0.1

Including --pause prevents the bag from playing immediately. Press space to unpause and begin playing.

The -r 0.1 limits the bag playback to 1/10th of real-time. This may be necessary to prevent packets from being dropped.

In a third terminal you can check that the topics are available

rostopic list

You should see the topics from your bag

user@VirtualBox:~$ rostopic list
/clock
/os1_node/imu_packets
/os1_node/lidar_packets
/rosout
/rosout_agg

Now you can launch the rosbridge server

roslaunch rosbridge_server rosbridge_websocket.launch

The default configuration opens the websocket on port 9090, which is precofigured in the client source code.

Finally, you can launch the client app

./bagman.elf

Troubleshooting

If something fails it's probably due to the setup files not being sourced; try re-opening the shell, or source them manually:

source /opt/ros/melodic/setup.bash
source path/to/myworkspace/devel/setup.bash

*I didn't try to understand how ROS works, I just needed to do this thing, so some steps may be unnecessary or inefficient